LA1: Three point lighting tutorial

The three point lighting system uses three different point sources - key light, fill light and edge light - for specific purposes.

Key Light

The key light is your main light source and is the strongest and brightest. It is the one that illuminates the subject. If you only have one light source lighting up your subject, that makes it your key light. When shooting an object or person, we almost always want the front to be illuminated and clear - this is why majority of 

the time the main light source is located in front of your subject. With more knowledge you could use 

the key light from any direction you like, not just from the front.

Fill Light

Already in its name, the fill light fill's the space that isn't full. Fill light is used when e.g. a photo is taken with light used so there will be a shadow that you may not want. The fill light would shine where the shadow is and replace it with light rather than shade. It is basically used to fill in the shadows that aren't wanted and to add light to lighten or soften the shadow.

The strength of the fill light can vary depending on your preference, but typically the fill light is always weaker than the key light. 

When in studio lighting, ratios tend to be used and it is common to have a lighting ratio of 2:1.

Back Light

The back light is placed behind the subject and lights it from the rear. Rather than providing direct lighting ( like the key and fill ), its purpose is to provide definition and subtle highlights around the subjects outlines. This helps separate the subject fro the background and provide a three-dimensional look. 

It is used to create separation between the subject and the background that they don't disappear into it.  It achieves this by creating a highlight around the outline of the subject.